Geochemistry-Inspired One-Pot CO2 Reduction and Pyrite Desulfurization Under Hydrothermal Conditions

Pyrite, as a potential raw material for iron making, is widely and abundantly distributed on Earth. However, sulfur pollution significantly limits its application in iron making. Inspired by abiotic CO2 reduction into organics in deep-sea hydrothermal vents and Earth's crust, in which H2S acts as an important reductant, we propose a novel method for hydrothermal reduction of CO2 using pyrite as a reductant with a simultaneous pyrite desulfurization. Results showed that the CO2 was converted to formic acid with a selectivity of nearly 100%, along with the desulfurization of pyrite to generate magnetite (Fe3O4) and sulfate. We found that the in situ-produced Fe3O4 had rich oxygen vacancies due to the formation of FeCO3 intermediate, which further enhanced the adsorption and activation of in situ-produced hydrogen and its subsequent hydrogenation with HCO3– to generate formate. This study provides a new method for solving problems of both seeking cheap and abundant hydrogen sources for CO2 reduction and reducing high sulfur pollution of traditional pyrite desulfurization. It also further advances the theories of abiotic synthesis of organics.